一种测量薄膜电阻器微弱噪声的放大电路设计

摘要

In view of the measurement for the weak noise signal in thin-film resistor, a practical and low noise amplifier circuit of weak noise signal detection was designed. It was based on AD797 ultralow noise operational amplifier. The essentials of this circuit design were described from the aspects of the circuit form and device selection. At the same time, the performances of amplifier circuit were validated based on the experiment and the detection limit were discussed based on the theory respectively. The experimental results indicate that:the gain of this amplifier circuit is 1 210 in the wide frequency range of 10 Hz–10 MHz;the noise power spectral density at 100 Hz is only about 3.12×10–18 V2·Hz–1.%针对薄膜电阻器微弱噪声信号的检测，设计了一种实用化的基于 AD797集成运放芯片的低噪声放大电路。同时，在电路形式设计和器件选择两方面论述了放大电路设计要点，并在实验和理论的基础上分别进行了电路性能的验证和探测下限的讨论。实验结果表明：电路在10 Hz～10 MHz宽频带内的放大增益为1210倍；电路在100 Hz输出的噪声功率谱密度仅为3.12×10–18 V2·Hz–1。